The Characteristics Of Depositional Reservoirs And Diagenetic Evolution Process Of Third Sand Group In The Upper Part Of The Fourth Member Of Shahejie Formation In Yi 176 Area,Bonan Sag

In this paper,the Third Sand Group in the Upper Part of the fourth member of Shahejie Formation in Yi 176 area of Bonan sag is taken as the research object.Based on comprehensive theory of sequence stratigraphy,sedimentology,reservoir geology and petroleum geology,the data of drilling and logging and core testing and analysis are fully utilized,depositional reservoir characteristics and diagenetic evolution process were studied systematically.By identifying lithology mutation surface and small wash surface such as depositional interface,internal consensus in group three sand don't make 4 V level sequence interface VSB1 VSB2 VSB3 and VSB4,which could be divided into SSC1bottom-up SSC2 SSC3 three short-term cyclic sequence,and then through the sequence stratigraphic classification and the single well study well sequence stratigraphic correlation characteristics,such as the study area is established when the sequence stratigraphic framework.According to the rock color equal sedimentary structure logging facies marks,think three sand groups in the study area for the fan delta,nearshore subaqueous fan facies and lake facies mixed deposits,sedimentary facies classification scheme is established,including the main fan delta facies in the study area for the fan delta front deposition,the micro facies types including underwater distributary channel between underwater distributary channel and distributary mouth bar sand dam;The inshore underwater fan facies can be divided into three subfacies: root fan and end fan.The root of the fan mainly develops the main channel microfacies,including braided channel and interbraided channel microfacies,and the end of the fan mainly develops the fan end mud.Lake facies mainly for shore and shallow lake sedimentary,it can be divided into the beach bar and bar microfacies between dam and then waiting for the sequence stratigraphic framework,the single well sedimentary facies division even well profile correlation,sedimentary facies and the rise and fall to the short-term cycle half cycle phase domain as isochronous stratigraphic units compiled the planardistribution of sedimentary facies,has been clear about the three sand group of sedimentary facies in the study area on the lateral variation characteristics of superimposed transition relations and the sedimentary evolution process.The Third Sand Group in the Upper Part of the fourth member of Shahejie Formation in Yi 176 area,Bonan sag are mainly lithic feldspar sandstone and feldspar lithsandstone,and the pore types are mainly intergranular pores and intrgranular dissolved pores.The reservoir of The Third Sand Group mainly underwent compaction,cementation,dissolution and metasomatism,and was in the intermediate rock-forming A-B stage.Through the study of the controlled factors of reservoir development,it is found that the reservoir physical property is not only affected by the rock type,mineral composition and rock structure of the reservoir sand body itself,but also related to the sedimentary facies type,sedimentary stages and diagenesis experienced by the reservoir sand body in the later period.In sedimentary microfacies as the main body of reservoir evaluation,combined with the reservoir petrology,diagenesis,pore structure and physical properties characteristics established The Third Sand Group reservoir classification evaluation standard in the study area,The Third Sand Group reservoir could be divided into I,II,III classes,and then based on the plane distribution of sedimentary facies characteristics,composite sand body thickness isoline map,The Third Sand Group to predict the favorable reservoir distribution area,and by SSC1,SSC2,SSC3 sequence of each half cycle of falling is mapping unit created favorable reservoir prediction map.